1. Field of the Invention
The present invention relates to a control apparatus used for an image blur prevention apparatus for preventing an image blur caused by, e.g., a hand vibration.
2. Related Background Art
Conventionally, various kinds of photographing equipments, each consisting of a camera body having image pickup means and an exchangeable lens detachable from the body, i.e., single-lens reflex camera systems, which are assembled with an image blur correction mechanism, have been proposed.
For example, U.S. Pat. No. 4,965,619 filed by the assignee of the present application has made a proposal in which blur (vibration) detection means and image blur correction means are arranged in an exchangeable lens, and the start and end of an image blur correction operation are controlled in response to an operation of an operation member at the camera side.
On the other hand, Japanese Laid-Open Patent Application No. 3-192227 has made a proposal in which the image blur speed is detected by a two dimensional photosensitive sensor in a camera body, the detected blur speed is converted into a driving speed control value of a blur (vibration) correction lens, and the converted control value is transmitted to an exchangeable lens to control the driving operation of the blur correction lens, thereby suppressing an image blur.
Since a single-lens reflex camera is a product which has an importance as a system, it is desirable to arrange an element with a high value added or high cost in the camera side. From this viewpoint, a high-value added and high-cost element such as a blur detection sensor is preferably arranged in the camera side. On the other hand, since the image blur correction lens is arranged in the exchangeable lens, a control circuit of the lens is preferably arranged in the exchangeable lens. For this reason, in U.S. Pat. No. 4,965,619, since the exchangeable lens has a blur detection sensor, such a camera has poor expandability as a system, and the exchangeable lens becomes considerably expensive since it has both a blur correction optical mechanism and a blur detection sensor.
On the other hand, in Japanese Laid-Open Patent Application No. 3-192227, since the blur detection sensor is arranged in the camera body, such a camera fulfills the product concept of a single-lens reflex camera system, i.e., the arrangement of a high-value added element in the camera side. However, in this prior art, since the attribute of a signal between the camera and lens is fixed to be the blur speed, system expandability is poor. More specifically, upon development of a new camera body or exchangeable lens, it is a general practice to use best ones, at the time of development, of blur detection sensors and blur correction mechanisms to be arranged in them. However, for example, as a blur detection sensor, various kinds of sensors are available as follows:
Angular accelerometer: which detects the angular acceleration of a blur (vibration) by utilizing a servo effect between a mass member and a torquer coil.
Angular velocimeter: which detects the angular velocity of a blur by a vibration gyro, a gas-rate gyro, or a laser gyro.
Angular displacement meter: which detects the angular displacement of a blur by utilizing the inertia of a fluid in a cylindrical chamber.
Image blur displacement meter: which detects the displacement of an image by an image sensor.
Image blur velocimeter: which detects the motion vector (velocity) of an image by an image sensor.
Also, these sensors output signals having different attributes, i.e., an (angular) accelerations (angular) velocity, and (angular) displacement.
On the other hand, as driving control methods of a blur correction lens, the following methods are available:
a method using the displacement of a lens as a control object (reference value); and
a method using the velocity of a lens as a control object (reference value).
In this case, the control system is controlled based on the (angular) displacement and velocity of a blur.
For this reason, when the signal exchanged between the camera and lens is fixed to be, e.g., the blur speed, the range of blur sensors and blur correction lens methods which may be used is narrowed. On the other hand, the mount system of a single-lens reflex camera must normally be effective for a long period of time, and the compatibility of the mount systems must be maintained during this period of time. However, Japanese Laid-Open Patent Application No 3-192227 cannot provide a system which can flexibly cope with the pending problems, resulting in poor system expandability.
One aspect of the invention is an apparatus which is adapted to be used with a signal processing apparatus for use with an image blur prevention apparatus, and which comprises a determination portion for determining the relationship between the signal output characteristic of a signal output apparatus for outputting a signal to be input to the signal processing apparatus, and the signal processing characteristic of the signal processing apparatus, whereby a signal for image blur prevention is appropriately processed.